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Dik B, Parlak TM, Ates MB, Tufan O. Exploring the combined therapeutic efficacy of bexarotene and icariin in type 2 diabetic rats. J Pharm Pharmacol 2024:rgae100. [PMID: 39024515 DOI: 10.1093/jpp/rgae100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 07/03/2024] [Indexed: 07/20/2024]
Abstract
OBJECTIVES The aim of this study was to determine the single and combined antidiabetic activity and side effects of the retinoid X receptor agonist bexarotene and the thioredoxin-interacting protein inhibitor and peroxisome proliferator-activated receptor γ and AMP-activated protein kinase activator icariin. METHODS The rats were grouped as healthy (control), diabetes, diabetes + bexarotene (20 mg/kg), diabetes + icariin (60 mg/kg), diabetes + bexarotene (10 mg/kg) + icariin (30 mg/kg) low-dose combination and diabetes + bexarotene (20 mg/kg) + icariin (60 mg/kg) high-dose combination groups. KEY FINDINGS Icariin treatment led to a significant reduction in glucose levels compared with the diabetes control group, a remarkable outcome observed 45 days after the initial application. HbA1c levels of the icariin and low-dose combination treatment groups were significantly lower than in the diabetes group. Notably, icariin treatment also significantly elevated HOMA-β levels, which is indicative of improved β-cell function. Icariin significantly decreased glucose levels at 30 and 120 min in the oral glucose tolerance test. Moreover, it ameliorated hepatocyte degeneration, hepatic cord dissociation, congestion, mononuclear cell infiltration in the liver, and degeneration in the pancreas. CONCLUSIONS Icariin treatment exhibited robust antidiabetic effects with fewer side effects than other treatment options in this study. In future studies, long-term and varying doses of icariin will contribute to the development of novel antidiabetic drugs.
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Affiliation(s)
- Burak Dik
- Department of Pharmacology and Toxicology, Selcuk University, Konya, 42130, Türkiye
| | - Tugba Melike Parlak
- Department of Pharmacology and Toxicology, Selcuk University, Konya, 42130, Türkiye
| | | | - Oznur Tufan
- Department of Pharmacology and Toxicology, Selcuk University, Konya, 42130, Türkiye
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2
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Bánáti D, Hellman-Regen J, Mack I, Young HA, Benton D, Eggersdorfer M, Rohn S, Dulińska-Litewka J, Krężel W, Rühl R. Defining a vitamin A5/X specific deficiency - vitamin A5/X as a critical dietary factor for mental health. INT J VITAM NUTR RES 2024; 94:443-475. [PMID: 38904956 DOI: 10.1024/0300-9831/a000808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
A healthy and balanced diet is an important factor to assure a good functioning of the central and peripheral nervous system. Retinoid X receptor (RXR)-mediated signaling was identified as an important mechanism of transmitting major diet-dependent physiological and nutritional signaling such as the control of myelination and dopamine signalling. Recently, vitamin A5/X, mainly present in vegetables as provitamin A5/X, was identified as a new concept of a vitamin which functions as the nutritional precursor for enabling RXR-mediated signaling. The active form of vitamin A5/X, 9-cis-13,14-dehydroretinoic acid (9CDHRA), induces RXR-activation, thereby acting as the central switch for enabling various heterodimer-RXR-signaling cascades involving various partner heterodimers like the fatty acid and eicosanoid receptors/peroxisome proliferator-activated receptors (PPARs), the cholesterol receptors/liver X receptors (LXRs), the vitamin D receptor (VDR), and the vitamin A(1) receptors/retinoic acid receptors (RARs). Thus, nutritional supply of vitamin A5/X might be a general nutritional-dependent switch for enabling this large cascade of hormonal signaling pathways and thus appears important to guarantee an overall organism homeostasis. RXR-mediated signaling was shown to be dependent on vitamin A5/X with direct effects for beneficial physiological and neuro-protective functions mediated systemically or directly in the brain. In summary, through control of dopamine signaling, amyloid β-clearance, neuro-protection and neuro-inflammation, the vitamin A5/X - RXR - RAR - vitamin A(1)-signaling might be "one of" or even "the" critical factor(s) necessary for good mental health, healthy brain aging, as well as for preventing drug addiction and prevention of a large array of nervous system diseases. Likewise, vitamin A5/X - RXR - non-RAR-dependent signaling relevant for myelination/re-myelination and phagocytosis/brain cleanup will contribute to such regulations too. In this review we discuss the basic scientific background, logical connections and nutritional/pharmacological expert recommendations for the nervous system especially considering the ageing brain.
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Affiliation(s)
- Diána Bánáti
- Department of Food Engineering, Faculty of Engineering, University of Szeged, Hungary
| | - Julian Hellman-Regen
- Department of Psychiatry, Charité-Campus Benjamin Franklin, Section Neurobiology, University Medicine Berlin, Germany
| | - Isabelle Mack
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Tübingen, Germany
| | - Hayley A Young
- Faculty of Medicine, Health and Life Sciences, Swansea University, UK
| | - David Benton
- Faculty of Medicine, Health and Life Sciences, Swansea University, UK
| | - Manfred Eggersdorfer
- Department of Healthy Ageing, University Medical Center Groningen (UMCG), The Netherlands
| | - Sascha Rohn
- Department of Food Chemistry and Analysis, Institute of Food Technology and Food Chemistry, Technische Universität Berlin, Germany
| | | | - Wojciech Krężel
- Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Inserm U1258, CNRS UMR 7104, Université de Strasbourg, Illkirch, France
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Bohn T, Hellman-Regen J, de Lera AR, Böhm V, Rühl R. Human nutritional relevance and suggested nutritional guidelines for vitamin A5/X and provitamin A5/X. Nutr Metab (Lond) 2023; 20:34. [PMID: 37582723 PMCID: PMC10426203 DOI: 10.1186/s12986-023-00750-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 05/27/2023] [Indexed: 08/17/2023] Open
Abstract
In the last century, vitamin A was identified that included the nutritional relevant vitamin A1 / provitamin A1, as well as the vitamin A2 pathway concept. Globally, nutritional guidelines have focused on vitamin A1 with simplified recommendations and calculations based solely on vitamin A. The vitamin A / provitamin A terminology described vitamin A with respect to acting as a precursor of 11-cis-retinal, the chromophore of the visual pigment, as well as retinoic acid(s), being ligand(s) of the nuclear hormone receptors retinoic acid receptors (RARs) α, β and γ. All-trans-retinoic acid was conclusively shown to be the endogenous RAR ligand, while the concept of its isomer 9-cis-retinoic acid, being "the" endogenous ligand of the retinoid-X receptors (RXRs), remained inconclusive. Recently, 9-cis-13,14-dihydroretinoic acid was conclusively reported as an endogenous RXR ligand, and a direct nutritional precursor was postulated in 2018 and further confirmed by Rühl, Krezel and de Lera in 2021. This was further termed vitamin A5/X / provitamin A5/X. In this review, a new vitamin A5/X / provitamin A5/X concept is conceptualized in parallel to the vitamin A(1) / provitamin A(1) concept for daily dietary intake and towards dietary guidelines, with a focus on the existing national and international regulations for the physiological and nutritional relevance of vitamin A5/X. The aim of this review is to summarize available evidence and to emphasize gaps of knowledge regarding vitamin A5/X, based on new and older studies and proposed future directions as well as to stimulate and propose adapted nutritional regulations.
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Affiliation(s)
- Torsten Bohn
- Nutrition Research Group, Department of Precision Health, Luxembourg Institute and Health, 1 A-B, Rue Thomas Edison, 1445, Strassen, Luxembourg
| | - Julian Hellman-Regen
- Department of Psychiatry, Charité-Campus Benjamin Franklin, Section Neurobiology, University Medicine Berlin, Berlin, Germany
| | - Angel R de Lera
- Departamento de Química Orgánica, Facultad de Química, CINBIO and IBIV, Universidade de Vigo, Campus As Lagoas-Marcosende, 36310, Vigo, Spain
| | - Volker Böhm
- Institute of Nutritional Sciences, Friedrich Schiller University Jena, Jena, Germany
| | - Ralph Rühl
- CISCAREX UG, Transvaalstr. 27c, 13351, Berlin, Germany.
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4
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Devall M, Eaton S, Yoshida C, Powell SM, Casey G, Li L. Assessment of Colorectal Cancer Risk Factors through the Application of Network-Based Approaches in a Racially Diverse Cohort of Colon Organoid Stem Cells. Cancers (Basel) 2023; 15:3550. [PMID: 37509213 PMCID: PMC10377524 DOI: 10.3390/cancers15143550] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 07/03/2023] [Accepted: 07/07/2023] [Indexed: 07/30/2023] Open
Abstract
Numerous demographic factors have been associated with colorectal cancer (CRC) risk. To better define biological mechanisms underlying these associations, we performed RNA sequencing of stem-cell-enriched organoids derived from the healthy colons of seven European Americans and eight African Americans. A weighted gene co-expression network analysis was performed following RNA sequencing. Module-trait relationships were determined through the association testing of each module and five CRC risk factors (age, body mass index, sex, smoking history, and race). Only modules that displayed a significantly positive correlation for gene significance and module membership were considered for further investigation. In total, 16 modules were associated with known CRC risk factors (p < 0.05). To contextualize the role of risk modules in CRC, publicly available RNA-sequencing data from TCGA-COAD were downloaded and re-analyzed. Differentially expressed genes identified between tumors and matched normal-adjacent tissue were overlaid across each module. Loci derived from CRC genome-wide association studies were additionally overlaid across modules to identify robust putative targets of risk. Among them, MYBL2 and RXRA represented strong plausible drivers through which cigarette smoking and BMI potentially modulated CRC risk, respectively. In summary, our findings highlight the potential of the colon organoid system in identifying novel CRC risk mechanisms in an ancestrally diverse and cellularly relevant population.
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Affiliation(s)
- Matthew Devall
- Department of Family Medicine, University of Virginia, Charlottesville, VA 22903, USA (L.L.)
| | - Stephen Eaton
- Department of Family Medicine, University of Virginia, Charlottesville, VA 22903, USA (L.L.)
| | - Cynthia Yoshida
- Digestive Health Center, University of Virginia, Charlottesville, VA 22903, USA
| | - Steven M. Powell
- Digestive Health Center, University of Virginia, Charlottesville, VA 22903, USA
| | - Graham Casey
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA 22908, USA;
- Department of Public Health Sciences, University of Virginia, Charlottesville, VA 22908, USA
| | - Li Li
- Department of Family Medicine, University of Virginia, Charlottesville, VA 22903, USA (L.L.)
- University of Virginia Comprehensive Cancer Center, University of Virginia, Charlottesville, VA 22908, USA
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5
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Chen G. The Interactions of Insulin and Vitamin A Signaling Systems for the Regulation of Hepatic Glucose and Lipid Metabolism. Cells 2021; 10:2160. [PMID: 34440929 PMCID: PMC8393264 DOI: 10.3390/cells10082160] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 08/17/2021] [Accepted: 08/19/2021] [Indexed: 02/07/2023] Open
Abstract
The pandemics of obesity and type 2 diabetes have become a concern of public health. Nutrition plays a key role in these concerns. Insulin as an anabolic hormonal was discovered exactly 100 years ago due to its activity in controlling blood glucose level. Vitamin A (VA), a lipophilic micronutrient, has been shown to regulate glucose and fat metabolism. VA's physiological roles are mainly mediated by its metabolite, retinoic acid (RA), which activates retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which are two transcription factors. The VA status and activations of RARs and RXRs by RA and synthetic agonists have shown to affect the glucose and lipid metabolism in animal models. Both insulin and RA signaling systems regulate the expression levels of genes involved in the regulation of hepatic glucose and lipid metabolism. Interactions of insulin and RA signaling systems have been observed. This review is aimed at summarizing the history of diabetes, insulin and VA signaling systems; the effects of VA status and activation of RARs and RXRs on metabolism and RAR and RXR phosphorylation; and possible interactions of insulin and RA in the regulation of hepatic genes for glucose and lipid metabolism. In addition, some future research perspectives for understanding of nutrient and hormone interactions are provided.
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Affiliation(s)
- Guoxun Chen
- Department of Nutrition, University of Tennessee at Knoxville, Knoxville, TN 37996, USA
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6
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Ren G, Kim T, Kim HS, Young ME, Muccio DD, Atigadda VR, Blum SI, Tse HM, Habegger KM, Bhatnagar S, Coric T, Bjornsti MA, Shalev A, Frank SJ, Kim JA. A Small Molecule, UAB126, Reverses Diet-Induced Obesity and its Associated Metabolic Disorders. Diabetes 2020; 69:2003-2016. [PMID: 32611548 PMCID: PMC7458036 DOI: 10.2337/db19-1001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 06/18/2020] [Indexed: 12/13/2022]
Abstract
Targeting retinoid X receptor (RXR) has been proposed as one of the therapeutic strategies to treat individuals with metabolic syndrome, as RXR heterodimerizes with multiple nuclear receptors that regulate genes involved in metabolism. Despite numerous efforts, RXR ligands (rexinoids) have not been approved for clinical trials to treat metabolic syndrome due to the serious side effects such as hypertriglyceridemia and altered thyroid hormone axis. In this study, we demonstrate a novel rexinoid-like small molecule, UAB126, which has positive effects on metabolic syndrome without the known side effects of potent rexinoids. Oral administration of UAB126 ameliorated obesity, insulin resistance, hepatic steatosis, and hyperlipidemia without changes in food intake, physical activity, and thyroid hormone levels. RNA-sequencing analysis revealed that UAB126 regulates the expression of genes in the liver that are modulated by several nuclear receptors, including peroxisome proliferator-activated receptor α and/or liver X receptor in conjunction with RXR. Furthermore, UAB126 not only prevented but also reversed obesity-associated metabolic disorders. The results suggest that optimized modulation of RXR may be a promising strategy to treat metabolic disorders without side effects. Thus, the current study reveals that UAB126 could be an attractive therapy to treat individuals with obesity and its comorbidities.
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Affiliation(s)
- Guang Ren
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
| | - Teayoun Kim
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
| | - Hae-Suk Kim
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
| | - Martin E Young
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
| | - Donald D Muccio
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL
| | - Venkatram R Atigadda
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL
- Department of Dermatology, University of Alabama at Birmingham, Birmingham, AL
| | - Samuel I Blum
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL
| | - Hubert M Tse
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL
| | - Kirk M Habegger
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
| | - Sushant Bhatnagar
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
| | - Tatjana Coric
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL
| | - Mary-Ann Bjornsti
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL
| | - Anath Shalev
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
| | - Stuart J Frank
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
| | - Jeong-A Kim
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL
- UAB Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL
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7
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Shoucri BM, Hung VT, Chamorro-García R, Shioda T, Blumberg B. Retinoid X Receptor Activation During Adipogenesis of Female Mesenchymal Stem Cells Programs a Dysfunctional Adipocyte. Endocrinology 2018; 159:2863-2883. [PMID: 29860300 PMCID: PMC6669823 DOI: 10.1210/en.2018-00056] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 05/24/2018] [Indexed: 02/08/2023]
Abstract
Early life exposure to endocrine-disrupting chemicals (EDCs) is an emerging risk factor for the development of obesity and diabetes later in life. We previously showed that prenatal exposure to the EDC tributyltin (TBT) results in increased adiposity in the offspring. These effects linger into adulthood and are propagated through successive generations. TBT activates two nuclear receptors, the peroxisome proliferator-activated receptor (PPAR) γ and its heterodimeric partner retinoid X receptor (RXR), that promote adipogenesis in vivo and in vitro. We recently employed a mesenchymal stem cell (MSC) model to show that TBT promotes adipose lineage commitment by activating RXR, not PPARγ. This led us to consider the functional consequences of PPARγ vs RXR activation in developing adipocytes. We used a transcriptomal approach to characterize genome-wide differences in MSCs differentiated with the PPARγ agonist rosiglitazone (ROSI) or TBT. Pathway analysis suggested functional deficits in TBT-treated cells. We then compared adipocytes differentiated with ROSI, TBT, or a pure RXR agonist IRX4204 (4204). Our data show that RXR activators ("rexinoids," 4204 and TBT) attenuate glucose uptake, blunt expression of the antidiabetic hormone adiponectin, and fail to downregulate proinflammatory and profibrotic transcripts, as does ROSI. Finally, 4204 and TBT treatment results in an inability to induce markers of adipocyte browning, in part due to sustained interferon signaling. Taken together, these data implicate rexinoids in the development of dysfunctional white adipose tissue that could potentially exacerbate obesity and/or diabetes risk in vivo. These data warrant further screening and characterization of EDCs that activate RXR.
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Affiliation(s)
- Bassem M Shoucri
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California
- Medical Scientist Training Program, University of California, Irvine, Irvine, California
| | - Victor T Hung
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California
| | - Raquel Chamorro-García
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California
| | - Toshi Shioda
- Center for Cancer Research, Massachusetts General Hospital, Charlestown, Massachusetts
| | - Bruce Blumberg
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California
- Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, California
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California
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8
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Xu Y, O'Malley BW, Elmquist JK. Brain nuclear receptors and body weight regulation. J Clin Invest 2017; 127:1172-1180. [PMID: 28218618 DOI: 10.1172/jci88891] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Neural pathways, especially those in the hypothalamus, integrate multiple nutritional, hormonal, and neural signals, resulting in the coordinated control of body weight balance and glucose homeostasis. Nuclear receptors (NRs) sense changing levels of nutrients and hormones, and therefore play essential roles in the regulation of energy homeostasis. Understanding the role and the underlying mechanisms of NRs in the context of energy balance control may facilitate the identification of novel targets to treat obesity. Notably, NRs are abundantly expressed in the brain, and emerging evidence indicates that a number of these brain NRs regulate multiple aspects of energy balance, including feeding, energy expenditure and physical activity. In this Review we summarize some of the recent literature regarding effects of brain NRs on body weight regulation and discuss mechanisms underlying these effects.
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Lewis JE, Brameld JM, Hill P, Wilson D, Barrett P, Ebling FJP, Jethwa PH. Thyroid hormone and vitamin D regulate VGF expression and promoter activity. J Mol Endocrinol 2016; 56:123-34. [PMID: 26643910 PMCID: PMC4705542 DOI: 10.1530/jme-15-0224] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/03/2015] [Indexed: 01/20/2023]
Abstract
The Siberian hamster (Phodopus sungorus) survives winter by decreasing food intake and catabolizing abdominal fat reserves, resulting in a sustained, profound loss of body weight. Hypothalamic tanycytes are pivotal for this process. In these cells, short-winter photoperiods upregulate deiodinase 3, an enzyme that regulates thyroid hormone availability, and downregulate genes encoding components of retinoic acid (RA) uptake and signaling. The aim of the current studies was to identify mechanisms by which seasonal changes in thyroid hormone and RA signaling from tanycytes might ultimately regulate appetite and energy expenditure. proVGF is one of the most abundant peptides in the mammalian brain, and studies have suggested a role for VGF-derived peptides in the photoperiodic regulation of body weight in the Siberian hamster. In silico studies identified possible thyroid and vitamin D response elements in the VGF promoter. Using the human neuroblastoma SH-SY5Y cell line, we demonstrate that RA increases endogenous VGF expression (P<0.05) and VGF promoter activity (P<0.0001). Similarly, treatment with 1,25-dihydroxyvitamin D3 increased endogenous VGF mRNA expression (P<0.05) and VGF promoter activity (P<0.0001), whereas triiodothyronine (T3) decreased both (P<0.01 and P<0.0001). Finally, intra-hypothalamic administration of T3 blocked the short day-induced increase in VGF expression in the dorsomedial posterior arcuate nucleus of Siberian hamsters. Thus, we conclude that VGF expression is a likely target of photoperiod-induced changes in tanycyte-derived signals and is potentially a regulator of seasonal changes in appetite and energy expenditure.
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Affiliation(s)
- Jo E Lewis
- Division of Nutritional SciencesSchool of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UKSchool of Life SciencesUniversity of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UKThe Rowett Institute of Nutrition and HealthUniversity of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK Division of Nutritional SciencesSchool of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UKSchool of Life SciencesUniversity of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UKThe Rowett Institute of Nutrition and HealthUniversity of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK
| | - John M Brameld
- Division of Nutritional SciencesSchool of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UKSchool of Life SciencesUniversity of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UKThe Rowett Institute of Nutrition and HealthUniversity of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK
| | - Phil Hill
- Division of Nutritional SciencesSchool of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UKSchool of Life SciencesUniversity of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UKThe Rowett Institute of Nutrition and HealthUniversity of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK
| | - Dana Wilson
- Division of Nutritional SciencesSchool of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UKSchool of Life SciencesUniversity of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UKThe Rowett Institute of Nutrition and HealthUniversity of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK
| | - Perry Barrett
- Division of Nutritional SciencesSchool of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UKSchool of Life SciencesUniversity of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UKThe Rowett Institute of Nutrition and HealthUniversity of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK
| | - Francis J P Ebling
- Division of Nutritional SciencesSchool of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UKSchool of Life SciencesUniversity of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UKThe Rowett Institute of Nutrition and HealthUniversity of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK
| | - Preeti H Jethwa
- Division of Nutritional SciencesSchool of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UKSchool of Life SciencesUniversity of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UKThe Rowett Institute of Nutrition and HealthUniversity of Aberdeen, Bucksburn, Aberdeen AB21 9SB, UK
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10
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Identification of Bexarotene as a PPARγ Antagonist with HDX. PPAR Res 2015; 2015:254560. [PMID: 26451138 PMCID: PMC4586960 DOI: 10.1155/2015/254560] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/23/2015] [Indexed: 12/17/2022] Open
Abstract
The retinoid x receptors (RXRs) are the pharmacological target of Bexarotene, an antineoplastic agent indicated for the treatment of cutaneous T cell lymphoma (CTCL). The RXRs form heterodimers with several nuclear receptors (NRs), including peroxisome proliferator-activated receptor gamma (PPARγ), to regulate target gene expression through cooperative recruitment of transcriptional machinery. Here we have applied hydrogen/deuterium exchange (HDX) mass spectrometry to characterize the effects of Bexarotene on the conformational plasticity of the intact RXRα:PPARγ heterodimer. Interestingly, addition of Bexarotene to PPARγ in the absence of RXRα induced protection from solvent exchange, suggesting direct receptor binding. This observation was confirmed using a competitive binding assay. Furthermore, Bexarotene functioned as a PPARγ antagonist able to alter rosiglitazone induced transactivation in a cell based promoter:reporter transactivation assay. Together these results highlight the complex polypharmacology of lipophilic NR targeted small molecules and the utility of HDX for identifying and characterizing these interactions.
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Prashanth A, Jeyakumar SM, Singotamu L, Harishankar N, Giridharan NV, Vajreswari A. Mitochondriogenesis and apoptosis: possible cause of vitamin A-mediated adipose loss in WNIN/Ob-obese rats. Nutr Metab (Lond) 2014; 11:45. [PMID: 25302071 PMCID: PMC4190477 DOI: 10.1186/1743-7075-11-45] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 09/11/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Previously, we reported that vitamin A-enriched diet (129 mg/kg diet) intake reduces the adiposity development in obese rats of WNIN/Ob strain. Here, we hypothesize that dose lesser than 129 mg of vitamin A/kg diet would also be effective in ameliorating the development of obesity in these rats. METHODS Five-month-old male lean and obese rats designated as A & B were divided into four subgroups (I, II, III and IV) consisting of 8 rats from each phenotype and received diets containing 2.6 mg (control group), 26 mg, 52 mg and 129 mg vitamin A/kg diet as retinyl palmitate for 20 weeks. Body composition and morphological analysis of brown adipose tissue (BAT) was analyzed. Expression of uncoupling protein 1 (UCP1), retinoic acid receptor α (RARα) and retinoid X receptor α (RXRα) in BAT and levels of Bcl2 and Bax in epididymal white adipose tissue (eWAT) were determined by immunoblotting. RESULTS Vitamin A supplementation to obese rats at doses of 52 and 129 mg/kg diet showed reduced body weight gain and adiposity compared to control diet-fed obese rats receiving 2.6 mg of vitamin A/kg diet. In BAT of obese rats, vitamin A supplementation at doses of 26 and 52 mg of vitamin A/kg diet resulted in increased UCP1 expression with concomitant decrease in RARα and RXRα levels compared to control diet-fed obese rats. Further, transmission electron microscopy study revealed an increase in number of BAT mitochondria of obese rats supplemented with 26 and 52 mg of vitamin A/kg diet. Also, obese rats fed on 52 mg/kg diet resulted in increased apoptosis by altering the ratio of Bcl2 to Bax protein levels in eWAT. Notably, most of these changes were not observed in lean rats fed vitamin A-enriched diets. CONCLUSION In conclusion, chronic consumption of 52 mg of vitamin A/kg diet seems to be an effective dose in ameliorating obesity possibly through mitochondriogenesis, UCP1-mediated thermogenesis in BAT and apoptosis in eWAT of obese rats. Therefore, the role of dietary vitamin A in correcting human obesity would be of unquestionable relevance and can only be addressed by future studies.
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Affiliation(s)
- Anamthathmakula Prashanth
- Department of Lipid Biochemistry, National Institute of Nutrition (ICMR), Jamai Osmania, Hyderabad, 500 007 Andhra Pradesh India
| | - Shanmugam M Jeyakumar
- Department of Lipid Biochemistry, National Institute of Nutrition (ICMR), Jamai Osmania, Hyderabad, 500 007 Andhra Pradesh India
| | - Lodhu Singotamu
- Ultra Structure Unit, National Institute of Nutrition (ICMR), Jamai Osmania, Hyderabad, 500 007 Andhra Pradesh India
| | - Nemani Harishankar
- National Center for Laboratory Animal Sciences (ICMR), Jamai-Osmania, Hyderabad, 500 007 Andhra Pradesh India
| | - Nappan V Giridharan
- National Center for Laboratory Animal Sciences (ICMR), Jamai-Osmania, Hyderabad, 500 007 Andhra Pradesh India
| | - Ayyalasomayajula Vajreswari
- Department of Lipid Biochemistry, National Institute of Nutrition (ICMR), Jamai Osmania, Hyderabad, 500 007 Andhra Pradesh India
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12
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Inoue M, Tanabe H, Nakashima KI, Ishida Y, Kotani H. Rexinoids isolated from Sophora tonkinensis with a gene expression profile distinct from the synthetic rexinoid bexarotene. JOURNAL OF NATURAL PRODUCTS 2014; 77:1670-1677. [PMID: 24959987 DOI: 10.1021/np5002016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The retinoid X receptor (RXR) plays a critical role in transcriptional regulation via formation of an RXR homodimer or heterodimers with partner nuclear receptors. Despite the numerous beneficial effects, only a limited number of naturally occurring RXR agonists are known. In this report, two prenylated flavanones (1 and 2) isolated from Sophora tonkinensis were identified as new rexinoids that preferentially activated RXRs, relative to the retinoic acid receptor. The activities of 1 and 2 were the most potent among naturally occurring rexinoids, yet 2 orders of magnitude lower than the synthetic rexinoid bexarotene. Compounds 1 and 2 activated particular RXR heterodimers in a manner similar to bexarotene. A microarray assay followed by quantitative real-time polymerase chain reaction analyses on RNAs isolated from C2C12 myotubes treated with 1 or 2 demonstrated that they significantly increased mRNA levels of lipoprotein lipase, angiopoietin-like protein 4, and heme oxygenase-1. In contrast, bexarotene preferentially potentiated transcription of genes involved in lipogenesis and lipid metabolism such as sterol regulatory element-binding protein-1, fatty acid synthase, and apolipoprotein D by a liver X receptor agonist. In this study, we have demonstrated that two newly identified naturally occurring rexinoids, 1 and 2, possess properties different from bexarotene.
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Affiliation(s)
- Makoto Inoue
- Department of Pharmacology of Natural Compounds, Graduate School of Pharmaceutical Sciences, Aichi Gakuin University , 1-100 Kusumoto-cho, Chikusa-ku, Nagoya 464-8650, Japan
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13
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Ariyasu H, Yamada G, Iwakura H, Matsumura S, Inoue K, Kangawa K, Nakao K, Akamizu T. Reduction in circulating ghrelin concentration after maturation does not affect food intake. Endocr J 2014; 61:1041-52. [PMID: 25029956 DOI: 10.1507/endocrj.ej14-0255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Ghrelin has a potent orexigenic effect and induces adiposity when administered exogenously. Since plasma ghrelin levels rise before meals, ghrelin was thought to play a crucial role in the regulation of appetite. In contrast, mice deficient in the production of ghrelin or the corresponding receptor, GHS-R, do not eat less, throwing the role of ghrelin in the regulation of energy homeostasis into question. Since these mice lack ghrelin or GHS-R from the time of conception, the possibility that compensatory mechanisms may have arisen during development cannot be ruled out. In this study, we used a transgenic mouse model that expresses human diphtheria toxin (DT) receptor cDNA under the control of the ghrelin promoter (GPDTR-Tg mice). As previously reported, an injection of DT into this mouse model ablates ghrelin-secreting cells in the stomach but not in the hypothalamus, resulting in a reduction in circulating ghrelin levels. We used this model system to evaluate the physiological roles of circulating ghrelin in the regulation of food intake. Meal patterns, diurnal and nocturnal meal sizes, and cumulative food intake of DT-treated GPDTR-Tg mice were not affected, although circulating ghrelin levels markedly decreased even after fasting. These mice also displayed normal responses to starvation; however, the use of fat increased and slower weight gain when maintained on a high fat diet was observed. Together, these data suggest that circulating ghrelin does not play a crucial role in feeding behavior, but rather is involved in maintaining body weight.
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Affiliation(s)
- Hiroyuki Ariyasu
- Department of Endocrinology and Metabolism, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan
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14
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Goebel-Stengel M, Stengel A, Wang L, Ohning G, Taché Y, Reeve JR. CCK-8 and CCK-58 differ in their effects on nocturnal solid meal pattern in undisturbed rats. Am J Physiol Regul Integr Comp Physiol 2012; 303:R850-60. [PMID: 22874423 DOI: 10.1152/ajpregu.00365.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Various molecular forms of CCK reduce food intake in rats. Although CCK-8 is the most studied form, we reported that CCK-58 is the only detectable endocrine peptide form in rats. We investigated the dark-phase rat chow intake pattern following injection of CCK-8 and CCK-58. Ad libitum-fed male Sprague-Dawley rats were intraperitoneally injected with CCK-8, CCK-58 (0.6, 1.8, and 5.2 nmol/kg), or vehicle. Food intake pattern was assessed during the dark phase using an automated weighing system that allowed continuous undisturbed monitoring of physiological eating behavior. Both CCK-8 and CCK-58 dose dependently reduced 1-h, dark-phase food intake, with an equimolar dose of 1.8 nmol being similarly effective (-49% and -44%). CCK-58 increased the latency to the first meal, whereas CCK-8 did not. The intermeal interval was reduced after CCK-8 (1.8 nmol/kg, -41%) but not after CCK-58. At this dose, CCK-8 increased the satiety ratio by 80% and CCK-58 by 160%, respectively, compared with vehicle. When behavior was assessed manually, CCK-8 reduced locomotor activity (-31%), whereas grooming behavior was increased (+59%). CCK-58 affected neither grooming nor locomotor activity. In conclusion, reduction of food intake by CCK-8 and CCK-58 is achieved by differential modulation of food intake microstructure and behavior. These data highlight the importance of studying the molecular forms of peptides that exist in vivo in tissue and circulation of the animal being studied.
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Affiliation(s)
- Miriam Goebel-Stengel
- CURE: Digestive Diseases Research Center, Digestive Diseases Division, Department of Medicine, University of California, Los Angeles 90073, USA
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15
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Abstract
Retinoid acid is a metabolite of vitamin A and functions as an important factor in cell survival, differentiation and death. Most previous studies on retinoid metabolism have focused on its association with cancer, hematologic and dermatologic disorders. Given the special concern over the recent increase in the prevalence of diabetes worldwide, the role of retinoid metabolism on glucose metabolism and insulin resistance in the human body is of marked importance. Therefore, in this issue, we review the literature on the association of retinoid metabolism with glucose tolerance, with regard to insulin secretion, pancreatic autoimmunity, insulin sensitivity and lipid metabolism. Further, we tried to assess the possibility of using retinoids as a novel therapeutic strategy for diabetes.
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Affiliation(s)
- Eun-Jung Rhee
- Department of Endocrinology and Metabolism, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jorge Plutzky
- Cardiovascular Division, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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16
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Dawson MI, Xia Z. The retinoid X receptors and their ligands. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:21-56. [PMID: 22020178 DOI: 10.1016/j.bbalip.2011.09.014] [Citation(s) in RCA: 258] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 08/23/2011] [Accepted: 09/23/2011] [Indexed: 12/12/2022]
Abstract
This chapter presents an overview of the current status of studies on the structural and molecular biology of the retinoid X receptor subtypes α, β, and γ (RXRs, NR2B1-3), their nuclear and cytoplasmic functions, post-transcriptional processing, and recently reported ligands. Points of interest are the different changes in the ligand-binding pocket induced by variously shaped agonists, the communication of the ligand-bound pocket with the coactivator binding surface and the heterodimerization interface, and recently identified ligands that are natural products, those that function as environmental toxins or drugs that had been originally designed to interact with other targets, as well as those that were deliberately designed as RXR-selective transcriptional agonists, synergists, or antagonists. Of these synthetic ligands, the general trend in design appears to be away from fully aromatic rigid structures to those containing partial elements of the flexible tetraene side chain of 9-cis-retinoic acid. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Marcia I Dawson
- Cancer Center, Sanford-Burn Medical Research Institute, 10901 North Torrey Pines Rd., La Jolla, CA 93207, USA.
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17
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Modulation of RXR function through ligand design. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:57-69. [PMID: 21515403 DOI: 10.1016/j.bbalip.2011.04.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 04/06/2011] [Accepted: 04/07/2011] [Indexed: 12/22/2022]
Abstract
As the promiscuous partner of heterodimeric associations, retinoid X receptors (RXRs) play a key role within the Nuclear Receptor (NR) superfamily. Some of the heterodimers (PPAR/RXR, LXR/RXR, FXR/RXR) are "permissive" as they become transcriptionally active in the sole presence of either an RXR-selective ligand ("rexinoid") or a NR partner ligand. In contrast, "non-permissive" heterodimers (including RAR/RXR, VDR/RXR and TR/RXR) are unresponsive to rexinoids alone but these agonists superactivate transcription by synergizing with partner agonists. Despite their promiscuity in heterodimer formation and activation of multiple pathways, RXR is a target for drug discovery. Indeed, a rexinoid is used in the clinic for the treatment of cutaneous T-cell lymphoma. In addition to cancer RXR modulators hold therapeutical potential for the treatment of metabolic diseases. The modulation potential of the rexinoid (as agonist or antagonist ligand) is dictated by the precise conformation of the ligand-receptor complexes and the nature and extent of their interaction with co-regulators, which determine the specific physiological responses through transcription modulation of cognate gene networks. Notwithstanding the advances in this field, it is not yet possible to predict the correlation between ligand structure and physiological response. We will focus on this review on the modulation of PPARγ/RXR and LXR/RXR heterodimer activities by rexinoids. The genetic and pharmacological data from animal models of insulin resistance, diabetes and obesity demonstrate that RXR agonists and antagonists have promise as anti-obesity agents. However, the treatment with rexinoids raises triglycerides levels, suppresses the thyroid hormone axis, and induces hepatomegaly, which has complicated the development of these compounds as therapeutic agents for the treatment of type 2 diabetes and insulin resistance. The discovery of PPARγ/RXR and LXR/RXR heterodimer-selective rexinoids, which act differently than PPARγ or LXR agonists, might overcome some of these limitations.
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18
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Cameron KM, Speakman JR. The extent and function of 'food grinding' in the laboratory mouse (Mus musculus). Lab Anim 2010; 44:298-304. [PMID: 20457827 DOI: 10.1258/la.2010.010002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Many laboratory rodents grind their food into crumbs that are discarded at the bottom of the cage (sometimes called orts). This can have substantial impacts on measures of food intake and assimilation efficiency. We quantified food grinding in two laboratory mouse strains on eight different diets and distinguished between two hypotheses of why food grinding occurs: a stereotypic behaviour due to a lack of environmental enrichment, or part of an optimal food intake strategy. Orts were quantified when mice were exposed to environmental enrichment and when offered diets of differing energetic quality. Grinding was significantly different between diets, but not between strains, although there was a significant diet by strain interaction. Ort production was lowest on the hardest diets. Not accounting for orts could affect food intake estimates by up to 31.8% and assimilation efficiency by up to 16.7%. Environmental enrichment increased physical activity, but did not reduce grinding. Mice selected the higher energy density components of the food. We suggest a refinement of the current methodology for measuring food intake is essential, primarily because failure to take ort production into account created inaccurate estimates of food intake and assimilation efficiency in mice. Adding environmental enrichment is unlikely to reduce food grinding, but careful choice of diet will reduce the errors.
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Affiliation(s)
- K M Cameron
- Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK.
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19
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Shearer KD, Goodman TH, Ross AW, Reilly L, Morgan PJ, McCaffery PJ. Photoperiodic regulation of retinoic acid signaling in the hypothalamus. J Neurochem 2010; 112:246-57. [PMID: 19860856 DOI: 10.1111/j.1471-4159.2009.06455.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Both retinoic acid (RA) and thyroid hormone (TH) regulate transcription via specific nuclear receptors. TH regulates hypothalamic homeostasis and active T3 is generated by deiodinase enzymes in tanycytes surrounding the third ventricle. However, RA has not been previously considered in such a role. Data presented here highlights novel parallels between the TH and RA synthetic pathways in the hypothalamus implying that RA also acts to regulate hypothalamic gene expression and function. Key elements of the RA cellular signaling pathway were shown to be regulated in the rodent hypothalamus. Retinoid synthetic enzymes and the retinol transport protein Stra6 were located in the cells lining the third ventricle allowing synthesis of RA from retinol present in the CNS to act via RA receptors and retinoid X receptors in the hypothalamus. Photoperiod manipulation was shown to alter the expression of synthetic enzymes and receptors with lengthening of photoperiod leading to enhanced RA signaling. In vitro RA can regulate the hypothalamic neuroendocrine peptide adrenocorticotrophic hormone. This work presents the new concept of controlled RA synthesis by hypothalamic tanycytes giving rise to possible involvement of this system in endocrine, and possibly vitamin A, homeostasis.
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Affiliation(s)
- Kirsty D Shearer
- Institute of Medical Sciences, School of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, UK
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20
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Abstract
Many different drugs affect thyroid function. Most of these drugs act at the level of the thyroid in patients with normal thyroid function, or at the level of thyroid hormone absorption or metabolism in patients requiring exogenous levothyroxine. A small subset of medications including glucocorticoids, dopamine agonists, somatostatin analogues and rexinoids affect thyroid function through suppression of TSH in the thyrotrope or hypothalamus. Fortunately, most of these medications do not cause clinically evident central hypothyroidism. A newer class of nuclear hormone receptors agonists, called rexinoids, cause clinically significant central hypothyroidism in most patients and dopamine agonists may exacerbate 'hypothyroidism' in patients with non-thyroidal illness. In this review, we explore mechanisms governing TSH suppression of these drugs and the clinical relevance of these effects.
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Affiliation(s)
- Bryan R Haugen
- University of Colorado Denver, School of Medicine, Department of Medicine, Division of Endocrinology, Metabolism and Diabetes, MS 8106, PO box 6511, Aurora, CO 80045, USA.
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21
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Macejová D, Križanová O, Brtko J. Different mRNA expression profiling of nuclear retinoid, thyroid, estrogen and PPARgamma receptors, their coregulators and selected genes in rat liver and spleen in response to short-term in vivo administration of 13-cis retinoic acid. Toxicol Lett 2009; 184:114-20. [DOI: 10.1016/j.toxlet.2008.10.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 10/27/2008] [Accepted: 10/28/2008] [Indexed: 11/26/2022]
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22
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Alaynick WA. Nuclear receptors, mitochondria and lipid metabolism. Mitochondrion 2008; 8:329-37. [PMID: 18375192 PMCID: PMC2831104 DOI: 10.1016/j.mito.2008.02.001] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2007] [Revised: 01/29/2008] [Accepted: 02/15/2008] [Indexed: 01/29/2023]
Abstract
Lipid metabolism is a continuum from emulsification and uptake of lipids in the intestine to cellular uptake and transport to compartments such as mitochondria. Whether fats are shuttled into lipid droplets in adipose tissue or oxidized in mitochondria and peroxisomes depends on metabolic substrate availability, energy balance and endocrine signaling of the organism. Several members of the nuclear hormone receptor superfamily are lipid-sensing factors that affect all aspects of lipid metabolism. The physiologic actions of glandular hormones (e.g. thyroid, mineralocorticoid and glucocorticoid), vitamins (e.g. vitamins A and D) and reproductive hormones (e.g. progesterone, estrogen and testosterone) and their cognate receptors are well established. The peroxisome-proliferator activated receptors (PPARs) and liver X receptors (LXRs), acting in concert with PPARgamma Coactivator 1alpha (PGC-1alpha), have been shown to regulate insulin sensitivity and lipid handling. These receptors are the focus of intense pharmacologic studies to expand the armamentarium of small molecule ligands to treat diabetes and the metabolic syndrome (hypertension, insulin resistance, hyperglycemia, dyslipidemia and obesity). Recently, additional partners of PGC-1alpha have moved to the forefront of metabolic research, the estrogen-related receptors (ERRs). Although no endogenous ligands for these receptors have been identified, phenotypic analyses of knockout mouse models demonstrate an important role for these molecules in substrate sensing and handling as well as mitochondrial function.
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Affiliation(s)
- William A Alaynick
- Gene Expression Laboratory,The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, United States.
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23
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Altucci L, Leibowitz MD, Ogilvie KM, de Lera AR, Gronemeyer H. RAR and RXR modulation in cancer and metabolic disease. Nat Rev Drug Discov 2007; 6:793-810. [PMID: 17906642 DOI: 10.1038/nrd2397] [Citation(s) in RCA: 397] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Retinoic acid receptors (RARs) are ligand-controlled transcription factors that function as heterodimers with retinoid X receptors (RXRs) to regulate cell growth and survival. The success of RAR modulation in the treatment of acute promyelocytic leukaemia (APL) has stimulated considerable interest in the development of RAR and RXR modulators. This has been aided by recent advances in the understanding of the biological role of RARs and RXRs and in the design of selective receptor modulators that might overcome the limitations of current drugs. Here, we discuss the challenges and opportunities for therapeutic strategies based on RXR and RAR modulators, with a focus on cancer and metabolic diseases such as diabetes and obesity.
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Affiliation(s)
- Lucia Altucci
- Dipartimento di Patologia Generale, Seconda Università degli Studi di Napoli, Vico Luigi de Crecchio 7, 80138 Napoli, Italy
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24
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Büttner MW, Burschka C, Daiss JO, Ivanova D, Rochel N, Kammerer S, Peluso-Iltis C, Bindler A, Gaudon C, Germain P, Moras D, Gronemeyer H, Tacke R. Silicon Analogues of the Retinoid Agonists TTNPB and 3-Methyl-TTNPB, Disila-TTNPB and Disila-3-methyl-TTNPB: Chemistry and Biology. Chembiochem 2007; 8:1688-99. [PMID: 17768726 DOI: 10.1002/cbic.200700182] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Twofold sila-substitution (C/Si exchange) in the saturated ring of the tetrahydronaphthalene skeleton of the retinoid agonists TTNPB (1 a) and 3-methyl-TTNPB (2 a) leads to disila-TTNPB (1 b) and disila-3-methyl-TTNPB (2 b), respectively. The silicon compounds 1 b and 2 b were synthesized in multiple steps, and their identities were established by elemental analyses, multinuclear NMR experiments, and single-crystal X-ray diffraction studies. Like TTNPB (1 a) and 3-methyl-TTNPB (2 a), the analogous silicon-based arotinoids 1 b and 2 b are strong pan-RAR agonists and display the same strong differentiation and apoptosis-inducing activity in NB4 promyelocytic leukemia cells as the parent carbon compounds. These results are in keeping with the nearly isomorphous structures of 1 a and 1 b bound to the complex of the RARbeta ligand-binding domain with the nuclear receptor (NR) box 2 peptide of the SRC-1 coactivator. The contacts within the ligand-binding pocket are identical except for helix H11, for which two turns are shifted in the disila-TTNPB (1 b) complex. This study represents the first comprehensive structure-function analysis of a carbon/silicon switch in a signaling molecule and demonstrates that silicon analogues can have the same biological functionalities and conserved structures as their parent carbon compounds, and it illustrates at the same time that silicon analogues of biologically active compounds have the potential to induce alternative allosteric effects, as in the case of helix H11, which might allow for novel options in drug design.
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Affiliation(s)
- Matthias W Büttner
- Universität Würzburg, Institut für Anorganische Chemie, Am Hubland, 97074 Würzburg, Germany
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25
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Pinaire JA, Reifel-Miller A. Therapeutic potential of retinoid x receptor modulators for the treatment of the metabolic syndrome. PPAR Res 2007; 2007:94156. [PMID: 17497022 PMCID: PMC1852898 DOI: 10.1155/2007/94156] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Revised: 01/04/2007] [Accepted: 01/04/2007] [Indexed: 01/30/2023] Open
Abstract
The increasing prevalence of obesity is a fundamental contributor
to the growing prevalence of the metabolic syndrome. Rexinoids, a
class of compounds that selectively bind and activate RXR,
are being studied as a potential option for the treatment of
metabolic syndrome. These compounds have glucose-lowering,
insulin-sensitizing, and antiobesity effects in animal models
of insulin resistance and type 2 diabetes. However,
undesirable side effects such as hypertriglyceridemia and
suppression of the thyroid hormone axis also occur.
This review examines and compares the effects of four RXR-selective
ligands: LGD1069, LG100268, AGN194204, and LG101506, a selective
RXR modulator. Similar to selective modulators of other nuclear
receptors such as the estrogen receptor (SERMs), LG101506
binding to RXR selectively maintains the desirable characteristic
effects of rexinoids while minimizing the undesirable effects.
These recent findings suggest that, with continued research efforts,
RXR-specific ligands with improved pharmacological profiles may
eventually be available as additional treatment options for the
current epidemic of obesity, insulin resistance, type 2 diabetes,
and all of the associated metabolic sequelae.
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Affiliation(s)
- Jane A. Pinaire
- Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285, USA
- *Jane A. Pinaire:
| | - Anne Reifel-Miller
- Lilly Research Laboratories, Lilly Corporate Center, Indianapolis, IN 46285, USA
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Golden WM, Weber KB, Hernandez TL, Sherman SI, Woodmansee WW, Haugen BR. Single-dose rexinoid rapidly and specifically suppresses serum thyrotropin in normal subjects. J Clin Endocrinol Metab 2007; 92:124-30. [PMID: 17062760 DOI: 10.1210/jc.2006-0696] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT Retinoid X receptor agonists (rexinoids) have demonstrated benefit in patients with certain malignancies but appear to cause central hypothyroidism in some patients with advanced cancer. The influence of rexinoids on thyroid function in healthy subjects is not clear. OBJECTIVE The objective of this study was to determine the effect of a single dose of bexarotene on levels of TSH, T4, and T3 in healthy subjects. DESIGN This study was a randomized, double-blind, placebo-controlled, crossover trial. SETTING This study was conducted at the General Clinical Research Center (University of Colorado Health Sciences Center, Aurora, CO). SUBJECTS Six healthy adults (>18 yr old) were studied. INTERVENTION Single-dose rexinoid (bexarotene, 400 mg/m2) or placebo, with TSH measurements at 0, 1, 2, 4, 8, 12, 24, and 48 h, were used. MAIN OUTCOME MEASURE The main outcome was the serum TSH level at 24 h. RESULTS Single-dose bexarotene suppressed serum TSH (P < 0.001) over time. Compared with placebo, levels of TSH were significantly lower by 12 h (P = 0.043); the nadir of 0.32 +/- 0.02 mU/liter (P < 0.001) was seen at 24 h. Free T4 index and free T3 index were also significantly lower than placebo over time (48 h) (P = 0.029; P = 0.004, respectively). Serum prolactin, cortisol, and triglycerides were not affected (P > 0.05 for all). There was no significant effect of single-dose bexarotene on rT3 or T3/rT3 ratio at 24 h. CONCLUSION A single dose of a rexinoid can rapidly and specifically suppress serum TSH levels in healthy subjects. These data provide insight into the mechanisms by which rexinoids cause central hypothyroidism and potential ways this effect can be used for treatment of disorders such as thyroid hormone resistance and TSH-secreting pituitary tumors.
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Affiliation(s)
- Wendy M Golden
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado at Denver and Health Sciences Center, Building RC-1 South Tower, MS 8106; 12801 East 17th Avenue, PO Box 6511, Aurora, Colorado 80045, USA
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